The present invention relates to a new and improved bowl-type grinding apparatus.
In its more specific aspects, the present invention relates to a new and improved bowl-type grinding apparatus comprising a roll carrier at which there are mounted two or more grinding rolls, a grinding bowl which is mounted for rotation below the roll carrier about a substantially vertical axis on an axial thrust bearing, a drive means or arrangement for the grinding bowl arranged below the axial thrust bearing, and a speed reduction gear arrangement or gearing arranged between the drive means and the grinding bowl and comprising a substantially cylindrical housing which supports the axial thrust bearing and itself is supported by a substantially ring-shaped, outwardly protruding flange or flange member.
In a state-of-the-art bowl-type grinding apparatus of this kind as known, for example, from German Patent Publication No. 2,716,025, published Oct. 19, 1978, and specifically from FIG. 2 therein, the housing of the reduction gearing comprises a cylindrical upper housing member which is designed with a ring-shaped, outwardly protruding flange. This upper housing member is supported by means of such flange at a corresponding flange provided at the lower housing member and is secured thereto by being bolted thereat. The lower housing member rests on a base or foundation and conducts into the base the forces which are exerted by the grinding rolls on the grinding bowl and which are transmitted via the axial thrust bearing to the upper housing member. The lower housing member is thus heavily loaded during operation not only by axial forces, but also by forces acting in both the circumferential as well as in the radial direction. Such forces change with the operating conditions and as a function of the properties of the material to be ground and also cause bending moments. Therefore, deformations can not fail to occur in the lower housing member. These deformations adversely affect the speed reduction gearing as well as an angular gearing which precedes the speed reduction gearing as a component of the drive means and which is arranged in the same lower housing member as the speed reduction gearing. The tooth bearing or localized tooth contact of the gear teeth can markedly deteriorate as a consequence of the deformations appearing in the lower housing member. Additionally, also the upper housing member does not remain unaffected by the deformations appearing in the lower housing member, whereby also the bearing or load-supporting capability of the axial thrust bearing can significantly deteriorate.